Conventionally, for example, there is known a musical sound control device capable of periodically changing timbre of musical sound being generated, as described in the following PTL1. In this musical sound control device, the timbre of the musical sound is periodically changed by changing a cut-off frequency of a filter by using a low frequency signal. This musical sound control device includes a control, and a parameter defining a frequency of the low frequency signal is assigned to the control. That is, a value of the parameter is corresponded to an indicated value of the control. When the indicated value of the control is changed by a user operating the control, the frequency of the low frequency signal is changed in accordance with the indicated value.